1. Field of the Invention
The present invention relates to a roller blind for architectural openings, such as doors and windows. More specifically, the present invention relates to roller blinds with slats for providing directional shading.
2. Description of the Related Art
Various systems are known for controlling the amount of light that may pass through an architectural opening, such as a door or a window. Such systems are frequently used as aesthetic and/or functional door or window coverings.
One such system is a roller shade or blind. Roller blinds are manufactured from, for example, a woven fabric. Such blinds have a common aesthetic design, are typically lightweight and have a minimal amount of moving parts. The fabric winds compactly about a center roller when retracted, making the system easy to manipulate, e.g., carry and install.
Roller blinds have known problems. For example, traditional roller blinds, e.g., those having vinyl screens, tend to skew or shift along the longitudinal axis of the roller while the blind is being retracted. Once skewed, the roller could not be further retracted until the blind was extended and the shifted portion was properly realigned.
Another problem with typical blinds having vinyl screens is that the screens essentially block all light from passing into a space. As such, the space is either bathed in sunlight or very dark.
More recently, screens for roller blinds have been fabricated from a dense fiberglass core with a vinyl PVC coating. Such a screen, known as a fiberglass roll screen, often includes a plurality of spaced apart apertures which allow ambient light to pass into a room. The apertures, and therefore the blinds, are incapable of providing a directional shading of light. Rather, direct light passes through from all directions. Accordingly, the fabric must be sufficiently opaque to limit the passage of light, and in particular, direct sunlight. Screen fabric of this type typically has an open area of three to five percent of the total area of the screen.
On the other hand, horizontal slatted blind systems allow directional shading of light. However, such systems are less desirable to those seeking the simplicity, benefits and style of a roller type blind. For example, slatted systems require additional structure for rotating the slats to obtain the desired light directing characteristics. Slatted systems also require vertical ladder cords to maintain the slats in proper vertical, horizontal and angular orientation. To avoid the use of an abundance of ladder chords, slats need to be manufactured from rigid material, such as metal, wood, or rigid plastic, which adds significant weight.
An example of a typically complex slatted blind is disclosed in U.S. Pat. No. 4,722,382 to Vecchiarelli. This publication discloses utilizing a plurality of lift cords, which pass through holes in each slat and are secured to a bottom rail member. The lift cords may be pulled to raise or lower the slats relative to a headrail. The complexity of this system increases its cost as a whole and increases the likelihood that it will malfunction.
Yet other publications teach horizontally slatted blinds which are capable of being retracted in a rolled-up form. Two such publications include U.S. Pat. No. 2,012,887 to Major, granted on Aug. 27, 1935, and German Patent (Patentschrift) No. 70,451, granted in 1893.
The '887 publication discloses vertically extending strips and attachment members connecting slats to the strips. As illustrated in FIG. 2 of the publication, incorporated herein by reference, the slats have a radius of curvature which is greater than the radius of curvature for the roller. As such, the edges of the slats extend tangentially beyond the roller while the blind is retracted. Such a system is incapable of forming the compact configuration about the roller when the blind is retracted. Instead, the retracted blind forms a configuration which is bulky and difficult to manipulate.
The '451 publication discloses the opposite problem illustrated in the '887 publication. As illustrated in FIG. 3 of the '451 publication, incorporated herein by reference, the slats are formed with a constant curvature radius, which appears to be the curvature of the roller. Most slats will flex away from the roller as the blind is retracted. This is because the radius of the retracted blind increases as the blind is retracted. The end result, however, is the same as with the '887 publication. The retracted blind forms a configuration which is bulky and difficult to manipulate.
Another type of blind is disclosed in prior art Patent Specification Number GB 1,494,842, filed on Apr. 23, 1975 by Margaret L. Steel, incorporated herein by reference. The '842 publication illustrates in FIG. 9 and discloses at page 3, starting at line 63, a “temperature sensitive blind”. The blind has slats that are formed by bonding two plastics with different thermal expansion coefficients, so that the curvature of the slats changes as a function of temperature. For example, as the temperature rises, the slats flatten out. On the other hand, as the temperature lowers, the curvature of the slats increases.
Depending on the temperature, such temperature sensitive slats would exhibit problems associated with both the '887 and '451 publications. As the temperature decreases the curvature of the slats, the slats will extend tangentially beyond the roller while the blind is retracted. As the temperature increases the curvature of the slats, most slats will flex away from the roller as the blind is retracted. In either circumstance, the retracted blind forms a configuration which is bulky and difficult to manipulate.
In addition to the above stated issues in the art, another disadvantage of known blind systems is that they are generally designed to cover architectural openings on the inside of a building. Directional shading blinds have not been introduced which can be readily positioned in the interior or exterior due to the complexity of the design, resulting in a potential for failure in an exterior environment. The present invention fulfills this need.